The present invention relates to a connection structure and a method for fabricating the same and, more particularly, to a connection structure between a Si member and an Al member and to a method for fabricating the same.
In recent years, Micro-Electro-Mechanics (MEMS) has received attention as a technology for fabricating a minute and high-precision device and has been vigorously studied. The main stream of the MEMS technology is a fusion of multiple types of technologies such as semiconductor processing, machining, and electric circuit engineering, as shown in Japanese Laid-Open Patent Publication No. 2005-193336. The major characteristic feature of the main-stream technology is that the structure of a device is formed and embedded in a silicon wafer by etching.
By thus forming and embedding the structure of a device in a silicon wafer, an electronic circuit for driving and controlling the device can also be formed integrally on the same silicon wafer. Therefore, the main-stream technology is also advantageous in terms of device miniaturization and has been used for, e.g., the microphone of a mobile telephone or the like (see Japanese Laid-Open Patent Publication No. 2002-27595).
However, since the MEMS technology forms and embeds the structure of a device in a silicon wafer by etching, not only silicon but also aluminum, copper and the like which form wirings for the semiconductor device are also removed undesirably. It follows that, at the time at which the device structure is completed, silicon or silicon dioxide occupies the electrode portions of the device. To introduce external power into the device or input and output electric signals to and from the device, it is necessary to connect the device to an external circuit by some method. However, to perform wire bonding using gold wires, which is a simplest and most reliable connection method, a metal layer of Au, Al, or the like need to be formed in each of the electrode portions of the device by plating or the like. The formation of such a metal layer leads to a significant cost increase and causes the problem of a high-priced device.